Road construction apparatus and method

ABSTRACT

Disclosed is a method for constructing an asphalt-paved gutter, the gutter being of the type having a trough-shaped base and an asphalt layer defining the gutter which overlies the base. The method comprises screeding a surface with a shaping screed having the shaping profile of said trough-shaped base to form said trough-shaped base. The gutter is formed with an asphalt laydown machine, of the type used in road construction to spread asphalt over a base course and which screeds and compacts the asphalt using a floating screed, by providing a protuberance underneath the floating screed which protuberance is shaped and dimensioned to screed and compact the asphalt layer in use.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority of U.S. Provisional Patent Application No. 61/429,921 filed Jan. 5, 2011, the contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to the field of road construction.

BACKGROUND OF THE INVENTION

Asphalt is widely used for paving roads. For reasons including but not limited to cost, asphalt is typically applied in a relatively thin layer above a base course of compacted aggregate. Often, the base course is itself applied upon a compacted sub base course of compacted aggregate, this sub base aggregate having properties that differ from those of the base course aggregate. In a typical road building operation involving both base and sub base layers, elevated areas of the roadway are excavated to the depth of the required sub base. Thereafter, the sub base aggregate is applied in layers, rough graded and compacted, all by heavy equipment. This is followed by application of the base course aggregate which itself is applied in layers, rough graded and compacted, all by heavy equipment. The surface of the base course will then be machine graded, either through blading or compaction, in preparation for application of asphalt. The asphalt itself is usually applied by a self-propelled laydown machine, which receives granular asphalt material, for example, from a dump truck, spreads the asphalt over the base course, and then levels and partially compacts the asphalt with a floating screed. The partially-compacted asphalt is typically thereafter roll-compacted, to achieve a smooth finish and relatively impermeable surface.

All of the above is conventional, works relatively well and, being substantially mechanized, is relatively economical.

In some areas of the world it is desirable to include a paved gutter on the outer surface of the roadway for drainage. As the above-described equipment is adapted only for creating substantially planar roadways, it is known to provide paved gutters in a relatively non-mechanized fashion, with the base course and asphalt layers of the gutter area being formed and compacted with hand tools and small mechanized compaction devices. This adds to cost and complexity.

SUMMARY OF THE INVENTION

A method for constructing an asphalt-paved gutter comprises one aspect of the invention. In this method, the gutter is of the type having a trough-shaped base and an asphalt layer defining the gutter which overlies the base. This method comprises the steps of: screeding a surface with a shaping screed having the shaping profile of said trough-shaped base to form said trough-shaped base; and forming the gutter with an asphalt laydown machine. The laydown machine is of the type used in road construction to spread asphalt over a base course and which screeds and compacts the asphalt using a floating screed. The gutter is formed by providing a protuberance underneath the floating screed, which protuberance is shaped and dimensioned to screed and compact the asphalt layer in use.

According to another aspect of the invention, the surface can be defined by a layer of aggregate arranged in a strip alongside the base course of a roadway.

According to another aspect of the invention, the layer of aggregate arranged in a strip and the base course of a roadway can be constructed simultaneously and of identical construction.

According to another aspect of the invention, as the gutter is formed, the laydown machine can contemporaneously apply a layer of asphalt to the base course of the roadway.

According to another aspect of the invention, the shaping screed can be secured to the bucket of a front loader.

According to another aspect of the invention, the shaping screed can be secured to the bucket of a compact skid steer loader.

According to another aspect of the invention, the shaping screed can extend laterally outwardly and rearwardly from the bucket.

According to another aspect of the invention, the protuberance can be defined by: a base member having a surface which has a cross-section in the shape of the gutter profile; and a lip rigidly connected to the base member and adapted to be engaged by the floating screed in use to drag the base member with the surface of the base member presenting downwardly for compacting and shaping the asphalt.

According to another aspect of the invention, the protuberance can be coupled to the laydown machine by a link which is adapted to allow the protuberance to be moved without hand tools between the position underneath the floating screed and a position above the floating screed.

Other advantages, features and characteristics of the present invention, as well as methods of operation and functions of the related elements of the structure, and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following detailed description and the appended claims with reference to the accompanying figures, the latter being briefly described hereinafter.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a side schematic view of a prior art asphalt laydown machine;

FIG. 2 is a perspective view of an exemplary embodiment of the shaping screed used in the method;

FIG. 3 is a perspective view of an exemplary embodiment of the packer used in the method;

FIG. 4 is a view of the apparatus of FIG. 3 from another vantage point;

FIG. 5 is a view of a structure similar to the structure of FIG. 2 positioned for use; and

FIG. 6 is a view of the structure of FIG. 3 in use with the structure of FIG. 1.

DETAILED DESCRIPTION

Reference is initially made to FIGS. 2-4, which show apparatus 20A, 20B that embody aspects of the invention and which can be used to carry out a road-construction-related method that forms an exemplary embodiment of the invention. For greater certainty, it is hereinafter described that the method of the present invention is carried out, in part, with an asphalt laydown machine, of the general prior art type having a floating screed which is shown by way of example in FIG. 1 and identified with reference numeral 80, but it should be understood that the laydown machine 80 is illustrated for clarity only. Again, for clarity, only, the floating screed is identified in FIG. 1 with reference numeral 100.

FIG. 2 shows a shaping screed 20A which will be seen to comprise a blade 22 and a bracket 24. The blade 22 has a protruding tooth 26. The bracket 24 includes a base 28 arranged in angular relation to the blade 22, a pair of gussets 30 supporting the junction of the blade 22 and base 28 and a strut 32 rigidly extending between the base 28 and an intermediate portion of the blade 22. A plurality of apertures 34 are defined through the base 28.

A projecting lip 35 extends from the top of the blade 22 and a flag 37 projects upwardly from the blade end.

FIGS. 3 and 4 shows two sides of a packer 20B which comprises a base member 36, a face plate 38, a pair of chains 40 and a pair of nut and bolt assemblies 42. The base member 36 is shaped to define a trough 44. The face plate 38 is rigidly connected to the base member 36, occludes one end of the trough 44 and extends beyond the trough 44 to define a lip 46. The chains 40 are coupled to the face plate 38, with each chain 40 terminating in one of the nut and bolt assemblies 42.

Reference is now made to FIG. 5 and FIG. 6, which show, respectively, an apparatus similar to the apparatus of FIG. 2 and the apparatus of FIG. 3 positioned for use.

Turning first to FIG. 5, this shows the base 28 of the bracket 24 bolted (via apertures 34, not shown) to the bucket 48 of a compact skid steer loader (not shown), such that the blade 22 extends outwardly and rearwardly from the side of the bucket 48 and the tooth 26 projects downwardly. It is notable that the blade 22, exclusive of the tooth 26, should not be positioned above the base of the bucket 48 when operatively mounted.

Turning next to FIG. 6, this shows the base member 36 positioned beneath the floating screed 100 of the exemplary asphalt laydown machine 80 of FIG. 1, with the lip 46 projecting upwardly from the base member 36 to engage the screed 100. The chains 40 and nut and bolt assemblies 42, only partially shown, secure the packer 20B to the laydown machine 80.

In use, the roadway area is excavated and the base and sub base are prepared in a generally conventional manner, i.e.

-   -   the roadway is excavated, as required, to the depth of the base         and any required sub base     -   any required sub base is deposited and compacted     -   the base is deposited and compacted and graded as required to         receive asphalt

One notable practical requirement when carrying out the method of the present invention is that the base course be sufficiently wide to accommodate the required driving surface and any required gutter, i.e. a layer of aggregate for faulting the gutter is arranged in a strip alongside the base course of the intended roadway, with both portions being formed effectively simultaneously and of identical construction. [It is conceivable that the method of the present invention could be carried out in isolation, i.e. not as part of a roadway construction, but that would impact upon the economics and may not be advantageous in comparison to other known methods.]

Once the base course has been prepared, the apparatus 20A of FIG. 5 is used to screed the base course to form a trough in the base course, i.e. to form a trough-shaped base. To do so, the operator of the loader positions the shaping screed 20A such that the bottom of the blade 22, excluding the tooth 26, is level but slightly above the surface of the base course and drives the loader in a direction along the base course in a direction parallel to but offset from the intended location of the gutter. This causes the tooth 26 of the screed 20A to excavate the trough, and as the excavated material accumulates, it passes along the length of the blade 22 so as to be deposited to the side of the gutter. The lip 35 (not shown in the screed of FIG. 5) if provided as is advantageous, avoids overspill, i.e. it ensures that excavated material is deposited to the side of the gutter, rather than falling behind the blade.

In regard to excavation, it will be appreciated that the profile of the tooth of the shaping screed is a slightly elongated version of the desired trough; this, coupled with the angular orientation of the blade 22 when coupled to the bucket 48, provides for the tooth 26 to have a screeding profile, i.e. the profile of the tooth when viewed in the direction of vehicle travel, equivalent to the cross-sectional profile of the desired trough shaped base.

In this further regard, it is noted that ‘screeding’ often contemplates the preparation of a planar surface, but it is known to screed, for example, wet concrete with an arcuate board, to crown the surface, and thus, in this description and the appended claims, ‘screed’ should be understood to encompass all activities wherein a member is scraped/dragged along a surface to shape/profile the surface to match the scraping member.

The use of a compact skid steer loader will be understood to be advantageous, in that it is sufficiently lightweight to avoid much in the way of inadvertent dislodgement of the previously-prepared base course material, yet at the same time, is sufficiently powerful to excavate the trough relatively quickly. In order to ensure that the trough is correctly positioned, the operator will be required to drive the loader with some precision, but it will be appreciated that precision driving and bucket placement is a matter of routine to skilled operators and thus this operation is equally a matter of routine. The flag 37 assists in this regard, and also assists the operator in avoiding obstacles.

Once the trough has been defined in the base material, asphalt is applied using a laydown machine such as that shown in FIG. 1. The laydown machine operates in a generally conventional fashion, with the notable difference being that, instead of carefully driving the laydown machine to spread asphalt to the edge of the intended roadway, the machine will be operated to spread asphalt to the edge of the intended gutter. As well, the packer 20B is positioned underneath the screed plate 100 of the laydown machine, with the lip 46 engaged by the screed 100, as shown in FIG. 6. Thus, as the screed plate 100 of the laydown machine 80 creates the driving surface, the protuberance (defined by base member 36 and face plate 38), which has a cross-section in the shape of the desired gutter, is dragged by the lip 46 and compressed by the screed plate 100 to compact and shape the asphalt to form the desired gutter.

The chains 40 and nut and bolt assemblies 42 assist in terms of the positioning of the protuberance; without limitation, the chains and nut and bolt assemblies allow the screed plate of the laydown machine to be adjusted upwardly while in operation without disengagement of the protuberance. At the same time, when the protuberance defined by the packer 20B is not required, the chains allow that portion of the packer 20B that defines the protuberance to be removed from beneath the screed plate without tools and stowed for subsequent use.

After the laydown machine has completed its work, the roadway and gutter proper are finished. Run-off channels may be desired at points along the gutter, and these can be constructed and packed with hand tools and small mechanized compaction devices.

Whereas a single embodiment of the method is described and illustrated, variations are possible.

Without limitation, the screed 20A could be carried by a device other than a skid steer loader; other front loaders, for example, could readily be used.

As well, whereas the screed 20A has a tooth of a specific profile, other profiles are, of course, possible.

Further, whereas the packer 20B has a specific profile and structure, other profiles and structures are possible.

Additionally, the protuberance can be secured to the underside of the screed plate by means other than chains and nut and bolt assemblies.

Accordingly, the invention should be understood as limited only by the accompanying claims, purposively construed. 

1. A method for constructing an asphalt-paved gutter, the gutter being of the type having a trough-shaped base and an asphalt layer defining the gutter which overlies the base, the method comprising: screeding a surface with a shaping screed having the shaping profile of said trough-shaped base to form said trough-shaped base; and forming the gutter with an asphalt laydown machine, of the type used in road construction to spread asphalt over a base course and which screeds and compacts the asphalt using a floating screed, by providing a protuberance underneath the floating screed which protuberance is shaped and dimensioned to screed and compact the asphalt layer in use.
 2. A method according to claim 1, wherein the surface is defined by a layer of aggregate arranged in a strip alongside the base course of a roadway.
 3. A method according to claim 2, wherein the layer of aggregate arranged in a strip and the base course of a roadway are constructed simultaneously and are of identical construction.
 4. A method according to claim 3, wherein, as the gutter is formed, the laydown machine contemporaneously applies a layer of asphalt to the base course of the roadway.
 5. A method according to claim 3, wherein the screed is secured to the bucket of a front loader.
 6. A method according to claim 3, wherein the screed is secured to the bucket of a skid steer loader.
 7. A method according to claim 6, wherein the shaping screed extends laterally outwardly and rearwardly from the bucket.
 8. A method according to claim 4, wherein the protuberance is defined by a base member having a surface which has a cross-section in the shape of the gutter profile; and a lip rigidly connected to the base member and adapted to be engaged by the floating screed in use to drag the base member with the surface of the base member presenting downwardly for compacting and shaping the asphalt.
 9. A method according to claim 8, wherein the protuberance is coupled to the laydown machine by a link which is adapted to allow the protuberance to be moved without hand tools between the position underneath the floating screed and a position above the floating screed. 